.NET Creating Custom Tag Helpers in ASP.NET Core

Introduction

In ASP.NET Core, **Tag Helpers** are powerful tools that allow developers to create **HTML-like components** with server-side logic. This article explains how to build a **custom Tag Helper** to enhance your application and improve code reusability.

What are Tag Helpers in ASP.NET Core?

Tag Helpers allow **server-side code** to participate in **rendering HTML elements**. They provide an **HTML-friendly way** to work with **.NET Core MVC views**.

Creating a Custom Tag Helper

To create a custom **Tag Helper**, follow these steps:

using Microsoft.AspNetCore.Razor.TagHelpers;

public class CustomMessageTagHelper : TagHelper
{
    public string Message { get; set; }

    public override void Process(TagHelperContext context, TagHelperOutput output)
    {
        output.TagName = "div";
        output.Attributes.SetAttribute("class", "alert alert-info");
        output.Content.SetContent(Message);
    }
}

Implementing Custom Tag Helper in MVC

Register the Tag Helper in the **_ViewImports.cshtml** file:

@addTagHelper *, YourNamespace

Use the Tag Helper in a View:

<custom-message message="Hello from Tag Helper!"></custom-message>

Real-World Example: Custom Button Tag Helper

Let's create a **button tag helper** that applies Bootstrap styles dynamically.

public class ButtonTagHelper : TagHelper
{
    public string Type { get; set; } = "button";
    public string Class { get; set; } = "btn btn-primary";

    public override void Process(TagHelperContext context, TagHelperOutput output)
    {
        output.TagName = "button";
        output.Attributes.SetAttribute("type", Type);
        output.Attributes.SetAttribute("class", Class);
    }
}

Testing and Deployment

Run your application and test the **Tag Helper output** in the browser. Deploy using **Azure App Services** or **AWS Elastic Beanstalk**.

Conclusion

Tag Helpers are a **powerful feature** in ASP.NET Core that allows **cleaner, reusable, and more maintainable** HTML markup. Custom Tag Helpers make UI development **faster and more efficient**.